Procedure Add(X1, Y1, X2, Y2:Word; Thickness, Background:Word;
                  Picture:Pointer; Name:String; Special:Boolean; Key:Char)

    This adds a button to  your  object's  linked  list.  The screen area
    X1,Y1  to   X2,Y2   is   marked   as   a   button  and  is  allocated
    space on  the  heap  (not  for  screen  data  -  just  for  the above
    information).   Its  thickness,   background   colour   (what  colour
    the button is lying on),  picture,  name  and equivalent keys are all
    stored.  It is  then  allocated  a  unique  number.   This new button
    then becomes the current button.

    The button is not displayed.